The present invention is directed to a dual layer papermaking fabric which provides even drainage throughout and in which both the paper support surface and the machine contact surface are weft dominant surfaces.
Normally, dual layer papermaking fabrics are woven with a single set of warp threads, upper layer weft threads and lower layer weft threads. Normally, the number of upper layer weft threads is twice that of the lower layer weft threads. It is also desirable to have long weft floats on the paper support surface to provide a smooth surface with adequate permeability. The machine contact surface also preferably comprises long weft floats also for adequate permeability and further for protecting the warp threads against wear through excessive contact with the machine rolls.
Papermaking fabrics developed with these features in mind are disclosed in U.S. Pat. Nos. 4,739,803; 4,709,732; 5,025,839; 5,487,414; and 5,555,917.
The instant invention has for its object, a papermaking fabric having a paper support surface which is smooth so as to reduce fabric marking on the paper to a minimum.
Another object of the invention is a papermaking fabric having a paper support surface having machine direction crossover forming balanced twill lines which provide a minimum number of uniform markings on the paper.
Another object of the invention is providing a papermaking fabric having a minimum number of the warp threads exposed on the outer fabric surfaces providing increased wearability and improved uniformity.
Another object of the invention is a papermaking fabric which maintains even drainage during use.
Another object of the invention is a papermaking fabric having stabilized machine contact surface floats.
Another object of the invention is a papermaking fabric having stabilized support surface floats.
Another object of the invention is a papermaking fabric in which the warp crossovers on the paper support surface and the warp cross-unders on the machine contact surface form diagonal twill lines across each fabric surface.
Another object of the invention is a multi-layer papermaking fabric in which the weaves of each fabric layer are balanced.